Phased array ultrasonic testing (PAUT) is an advanced method of ultrasonic testing (UT) that has applications in industrial non-destructive testing (NDT). Common applications are to find flaws in manufactured materials such as welds.
Single-element (non-phased array) probes, known technically as monolithic probes, emit a beam in a fixed direction. To test a large volume of material, a conventional probe must be physically moved or turned to sweep the scan beam through the area of interest.
In contrast, the beam from a PAUT probe can be moved electronically, without moving the probe, and can be swept through a wide volume of material at high speed. The beam is controllable because a PAUT probe is made up of multiple small elements, each of which can be pulsed individually at a computer-calculated timing, forming incidence angles. The term phased refers to the timing, and the term array refers to the multiple elements. The element that contributes to a beam formation is defined as the aperture of the beam; the aperture can include a portion or all of the elements of the PAUT probe.
During typical inspections of welds, multiple ultrasound beams are generated from a single or multiple apertures at various incidence angles. These generate an image showing reflections (or diffractions) of the ultrasonic waves that are associated to defects within the scanned area in the test object. For weld inspection, the interest area, or the scanned area is usually the weld and its surrounding area. For cases where the aperture is fixed and only the angles are changed, the images are called a sectorial scan or S-scan. For cases where the angle is fixed and only the aperture is moved, the images are called a linear scan or E-scan.
In order to have an appropriate coverage of the weld area, it is almost always required to combine inspections from both sides of a weld and it may also be required to do multiple passes on a given side of the weld if a single probe coverage proves insufficient. For defining an inspection plan, standards and normalized practice are the major factors composing the guidelines or codes for defining the probe and beam configurations, an example being Section V of ASME Boiler and Pressure Code—Nondestructive Examination. Such practices are referenced herein as code requirements. For weld inspection, the phased array configuration typically involves the use of a wedge, which defines a first mechanical incidence angle to generate an S-scan with shear waves in the 40 to 70 degree range of the refraction angle. The inspection of a complete weld area also involves a mechanical scan of the weld by moving the probe arrangement parallel to the weld axis.
According to an international code “2010 ASME Boiler & Pressure Vessel Code, 2010 Edition, Section V—Nondestructive Examination” (Herein after as “codes”), the definition of the inspection scan plan associated to weld inspection is as follows. This The scan plan is herein defined as the combination of,                a, instrumentation configuration including probe, wedge, and acquisition unit;        b, acoustic setting, including, aperture size and position, focalization setting, beams angle, gating parameters and,        c, probe manipulation guideline, including probe to weld distance, maximum inspection speed.        
A recurring problem associated to weld inspection using phased array ultrasonic scans is that the combination gets extremely complicated when all the variables, each could have vast range of selections are into play. It is extremely difficult to have an individual trained in such a broad range of expertise as in phased array systems, phased array probes and wedges and in weld structure and flaws.
As can be seen how stiff the challenge is to configure the right scan plan with ranges of parameters for all the factors listed above. A first approach being used in existing practice to address this problem is the use of modeling tools to visualize beams generated by the PAUT probe in the test object. Examples using this approach are “ESBeamTool” from Eclipse Scientific or “SetupBuilder” from Olympus. Whereas this approach to some degrees simplifies certain tasks such as weld coverage and probe placement, it does little to reduce the needs for high-level inspector expertise since a lot of knowledge is still required to bridge the gap between the codes requirement and the instrument selection, configuration and manipulation. More specifically, this approach does not automatically provide templates or models regarding the above listed aspects of a) and b) of a scan plan, and it does not automatically evaluate the above listed aspect c) for probe manipulation either.
Another solution to the problem of defining scan plans is the full integration of all the code requirements in the modeling software as disclosed in US Patent No. US20130218490. Even though this solution has certain success when integrated for the automated inspection of girth weld, when using a dedicated scanner it does have several drawbacks for the PAUT inspection of welds in general. Firstly, a significant amount of codes is needed for PAUT weld inspection in general because each group of codes represents the specific requirements associated to the specific weld usage (piping welds, boiler tubes, pressure vessels, etc.). Secondly, since code interpretation is complicated process and often without a straightforward answer, the code interpretation solely decided by a modeling tool does involve some potential responsibility and acceptance issues.
It would thus be desirable to have a computer aided tool that more easily generates a PAUT scan plan, yet still provides the desired flexibility to allow code requirement interpretation by duly qualified end-users.